Rotary shaft counter

ABSTRACT

A ROTARY SHAFT COUNTER IS CONSTRUCTED WITH A PLURALITY OF NUMBER DISKS EACH COUPLED TOBE CONTINUOUSLY DRIVEN IN COORDINATION WITH THE ROTATING SHAFT HAVING ITS REVOLUTIONS COUNTED. A MOVABLE LIGHT APERTURE PARTIALLY PROVIDED BY A TRANSPARENT SPIRAL ON ANOTHER DISK ROTATING IN COORDINATION WITH THE NUMBER DISKS, IS POSITIONED TO PASS A BEAM OF LIGHT FROM A SOURCE THROUGH TRANSPARENT INDICIA ON THE NUMBER DISKS TO PROJECT IMAGES OF SUCH INDICIA ON A GROUND GLASS DISPLAY SURFACE. THE SPIRAL LIGHT APERTURE   IS A SINGLE TURN HAVING SLIGHT OVERLAPPING END PORTIONS FORMING A CROSSOVER POINT FOR THE RAPID CHANGING OF THE DISPLAY PRESENTED BY THE NUMBER ON THE SLOWER MOVING OF THE NUMBER DISKS.

Feb.lz3,'1"971 H. B. BETTS 3,565,522

ROTARY SHAFT COUNTER Filed Aug.. i12. 196e s sheets-sheet 1 /7//////////// 4&1

INVENTOR.

Fl. 23, 1971 H. B. BVETTs l ROTARY SHAFT COUNTER -3 Sheets-Sheet 2 Filed Aug. *12, 1968 FelLNZS, 1971 H, B, BETTs 3,565,522

ROTARY SHAFT COUNTER Filed Aug. 12. 196e 3 Sheets-Sheet S INVENTOR. #aw/Ma a. 5.9/73

United States Patent C) 3,565,522 ROTARY SHAFT COUNTER Howard B. Betts, Mineola, N.Y., assignor to Vanguard Instrument Corporation, Melville, N.Y., a corporation of New York Filed Aug. 12, 1968, Ser. No. 751,863

Int. Cl. G03b 21/00 U.S. Cl. 353-41 10 Claims ABSTRACT OF THE DISCLOSURE A rotary shaft counter is constructed with a plurality of number disks each coupled to be continuously driven in coordination with the rotating shaft having its revolutions counted. A movable light aperture partially provided by a transparent spiral on another disk rotating in coordination with the number disks, is positioned to pass a beam of light from a source through transparent indicia on the number disks to project images of such indicia on a ground glass display surface. The spiral light aperture is a single turn having slight overlapping end portions forming a crossover point for the rapid changing of the display presented by the number on the slower moving of the number disks.

This invention relates to rotary shaft counters with digital displays in general and more particularly relates to a mechanical-optical means for displaying the reading of shaft position without introducing ambiguities into the readings.

Rotary shaft counters of the prior art for producing direct digital displays are generally of the type having a plurality of number wheels, usually one wheel for each significant figure being displayed. The wheels are connected by au intermittent drive mechanism -which is usually very noisy at high speed operation and must be of very rugged construction. Further, during operation of the higher order wheel ambiguities are prone to appear in the readings.

While electronic rotary shaft counters of the prior art are not plagued by the mechanical deficiencies noted above, such counters usually require expensive conversion devices to provide digital display.

In order to provide a high speed rotary shaft counter that does not suffer from those Adeficiencies of the prior art noted above, the instant invention utilizes a mechanical-optical structure for displaying the reading of shaft position and also for eliminating ambiguity in carrying readings. The basic mechanism consists of a plurality of number carrying disks driven at relative speeds to suit the counting rate desired. -T he mechanism to be hereinafter described is typical for producing 10() counts per revolution of the lowest order disk up to a count of 9,999.

No intermittent indexing type mechanisms are required to drive the higher order disks with a movable aperture being provided to avoid ambiguities which might other- Wise be present when utilizing continuously moving higher order disks. This moving aperture is provided by a transparent spiral formation on another disk driven in coordination with the number disks. A light beam transmitted through the transparent spiral as well as through portions of both number disks projects the shaft count on a display surface.

Ambiguity in the reading of the low significant gures is eliminated Vby providing a clear, yet not entirely transparent, marginal portion adjacent to the aperture forming spiral so that if the least significant figures are not centered in the aperture such figures may, nevertheless, be seen through the less transparent portion of the aperture.

Accordingly, a .primary object of the instant invention ice is to provide a novel construction for a rotary shaft counter with digital display of the count.

Another object is to provide a rotary shaft counter utilizing mechanical-optical means to eliminate the necessity for intermittent indexing type mechanisms.

Still another object is to provide an extremely fast, relatively quiet, and extremely reliable rotary shaft counting mechanism having a digital display.

A further object is to provide an optical means for eliminating ambiguity in the digital display of a high speed counter.

A still further object is to provde a zero reset structure for a high speed mechanical-optical rotary shaft counter with digital display.

These as well as other objects of the instant invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a perspective, in schematic form, showing a mechanical-optical rotary counter with digital display constructed in accordance with the teachings of the instant invention.

FIGS. 2, 2a, 3 and 3a are elevations at different manications of the high and low speed number disks respectively.

FIGS. 4 and 4a are elevations at different magnifications of the disk carrying the spiral light aperture.

FIGURES 5 and 6 are elevations of overlapping portions of the disks in the regions thereof contributing to the digital output appearing on the display surface. In FIG. 5 the displayed number contributed by the high speed disk is centered with respect to the spiral light aperture while in FIG. 6 the number is off center and would, but for provisions provided by the instant invention, provide an ambiguous reading.

FIGS. 7 and 8 show overlapping portions of the disks in the regions thereof contributing to the digital output appearing on the display surface during the crossover interval when there is a change of the higher order digits being displayed. In the embodiment of FIG. 7 the number of lower order digit bits or groups equals the number of the higher order digit bits while in the embodiment of FIG. 8 the number of lower order digit bits, including a blanking interval, exceeds by one the number of higher order digit bits.

FIG. 9 is a perspective showing the counter of FIG. 1 having a zero reset means added thereto.

Now referring to the figures and more particularly .to FIG. l which illustrates measuring device 10 for counting rotations of shaft 11 and producing a continuous digital display of the count readings. Input shaft 12 of device 10 is connected through coupling 13 for direct drive by shaft 11. When desired, the coupling between shafts 11 and 12 may change the relative speeds therebetween. Keyed to shaft 12 are number disk 14 and gear 17 and sprocket 1S with gear 17 being positioned forward of sprocket 18 and disk 14 being positioned between gear 17 and sprocket 18. Rotatably mounted on shaft 12 at a location between gear 17 and disk 14 is an assembly consisting of number disk 15 sleeve 19 and gear 21 with the later being positioned at the forward end of sleeve 19, and disk 15 being positioned at the rear end of sleeve 19.

Driving power for gear 21 is transmitted from gear 17 through speed reducing means consisting of gear 22 in mesh with gear 17, and gear 23 in mesh with gear 21, with both gears 22 and 23 being keyed to counter shaft 24 parallel to and laterally spaced from input shaft 12. It is noted that gear 21 is relatively large with respect to gear 17 and gear 22 is relatively large with respect to gear 23. Sprocket 18, acting through continuous chain 26, drives sprocket 27 keyed to shaft 28 at the rear end thereof. Shaft 28 is parallel to input shaft 12 and laterally spaced therefrom.

For reasons to be hereinafter explained, aperture disk 16 is keyed to shaft 28 at the forward end thereof and is positioned slightly to the rear of number disk 14. A projection system consisting of light source 31, lenses 32, 33 and ground glass display screen 34, is operatively positioned to present a digital display of shaft revolution counts on screen 34. In particular, the light beam emanating from source 31 is focused by lens 32 and directed from the rear of disks 14, 15, 16 forward therethrough and through magnifying lens 33 to be projected on display screen 34.

As seen in FIG. 2 number disk 14 is provided with a set of indicia consisting of a circular array of one hundred bits providing numbers from through 99. Even though these numbers are shown in the full View of disk 14 as being opaque against a clear background, this form of illustration is used merely because of size limitations. Actually in the embodiment of FIG. 1 the indicia along the periphery of number disk 14 is transparent against a dark background as shown in the er1- larged fragmentary portion of FIG. 2. More particularly, disk 14 is a transparent member having an opaque coating, selective portions of which are removed to provide a set of indicia adjacent to the disk periphery as well as a clear annular band 41 immediately to the inside of the set of indicia.

As best seen in FIG. 3, the construction of number disk 15 is essentially the same as the construction of disk 14 except that the clear band and set of indicia are in reversed positions. That is, for disk 15 clear band 43 is outside of the circular array of indicia consisting of one hundred bits providing numbers 00 through 99.

It is noted that number disks 14, 15 are of the same diameter and have the same diameter central aperture 44. Insert 14a (FIG. 1) in aperture 44 of number disk 14 keys the latter to input shaft 12 and-accommodates for the lesser diameter of shaft 12 as compared with the outer diameter of sleeve 19 to which number disk 15 is keyed.

As seen in FIG. 4, disk 16 is a transparent member having an opaque coating applied to areas 46, 47 thereof. Such opaque coatings 46, 47 are spaced from one another to form single turn transparent spiral or light aperture 48, the ends of which slightly overlap at crossover point 49 for reasons to be hereinafter explained. The center of spiral 48 is clear and colorless while the edge portions 48a, 481; are clear though less transparent being colored to restrict passage of some incident light while permitting viewers attention to be focused at the colorless central portion where more light is present.

It should be apparent that the two left-most digits on display screen 34 are derived from the set of indicia on number disk 15 while the two right-most digits appearing on screen 34 are derived from the set of indicia on number disk 14. Digital output 35 is the combined result of indicia bit 01. appearing on disk 15 and indicia bit 24 appearing on disk 14 being in alignment with a portion of spiral light aperture 48 of disk 16.

Since the relatively high speed disk 14 directly coupled to shaft 11 may not stop in an annular position which is equivalent to an exact least count, but may stop at a random position, the indicia bit projected from disk 14 screen 34 may not be centered with respect to the edge boundaries of light aperture 48. To avoid the possibility of ambiguity under such conditions the edges of light aperture 48 are provided with transparent colored strips 48a, 4811, usually dark red or dark green.

A typical situation is illustrated in FIGS. and 6. In FIG. 5 disk 14 is stopped in a position wherein indicia bit 24 thereof at the clear colorless central area of light aperture 48 and the reading 01.24 is unambiguous. However, if disk 14 had stopped with the indicia 24 off-center with respect to the colorless portion of light aperture 48 (see FIG. 6) then an ambiguity is present. If the light aperture extended only so far as the colorless central portion shown in FIGS. 5 and 6 an erroneous reading of 01.74 could possibly be taken. However, since the colored portions 48a, 48b of light aperture 48 are also present the entire indicia bit 24 derived from disk 14 is viewable at the colorless central portion of light aperture 48 and the less transparent colored portion 48a.

In the absence of aperture carrying disk 16, with shaft 12 rotating in a counterclockwise direction as indicated by arrow A in FIG. 1 the numbers appearing at display screen 34 and derived from relatively high speed disk 14 will move rapidly in a vertical direction upward and the numbers derived from disk 15 will also move toward but more slowly, at a speed ratio of 1 to 100. When the rotation of shaft 12 stops at any random position for the reading of shaft position an unsatisfactory and ambiguous display of numbers is shown on screen 34. Since the numbers move vertically across display screen 34, a fixed projection aperture will not place a border around the proper numbers for all conditions. However, the spiral light aperture 48 is carried iby disk 16 driven at a 1:1 ratio with respect to the speed of the faster number disk 14 provides a moving mask portion which causes only the currently correct numbers to be displayed by screen 34. The other mask portions are provided by clear annular bands 41, 43 on number disks 14, 15, respectively.

Spiral light aperture 48 performs the rapid changeover of number displayed from the slow speed number disk 15, when passing from between numbers 99 to 00 carried by high speed number disk 14. From the point of view of reducing ambiguity, this changeover must occur rapidly, say during the period of one change in the least count and preferably in a lesser period. This is accomplished by having the ends of the single turn spiral light aperture 48 overlap for angle K (FIG. 7) to form a so-called crossover point 49. As seen in FIG. 7, either reading 1.99 or 2.00 may be chosen by the operator as indicating the position for shaft 12 and either reading will be correct within one least count.

It is noted that the average radius of spiral light aperture 48 will determine the rapidity of the cutoff or shift to the next indicia bit for the higher order digits carried by number disk 15 during the period Awhen the lower order digits pass from 99 to 00. As a practical matter this radius can be made large enough so that the angle K is equivalent to that of a least count or smaller.

As previously described, lower order number disk 14 contains 100 equally spaced bits (00 to 99) along its rim. This produces a counting accuracy of plus or minus one hundredth of a turn of input shaft 12. A more accurate reading may be obtained by dividing the indicia bits on the higher speed disk 14 into 101 equal parts or bits consisting of numbers 00 to 99 and one blank or clear part between the positions 99 and 00 (see FIG. 8). This corrects for the effect of spiral aperture 48 during the progression of one revolution of shaft 12 as a whole revolution is being counted.

In particular, with the arrangement of FIG. 8 spiral light aperture 48 provides a mask which moves in the same direction as the numbers on the number disks and this continues up to the point where a transition from 99 to 00 occurs and the spiral mask transitions through the break in the spiral. The relative motion of the spiral and numbers disk produces an angular travel of 1 to 101 turns of the lowest order numbers disk, in the spiral area, for each 1 to 100 turns of input shaft 12. The numerical readout display is similar to that described in connection with FIGS. 1 through 7.

FIG. 9 shows a modified version of the structure of FIG. l including a zero reset means so that with the input shaft stopped at any position the apparatus may quickly and readily be set to zero in no more than a single turn of input shaft 12. More particularly, device 100 is for the most part the same as device so that corresponding structural elements are assigned the same reference numerals in both FIGS. 1 and 9 and no additional description of these elements will be given.

Shaft 11 acting through meshing gears 101, 102 and sliding coupling 103, drives input shaft 12 when gears 101, 102 are in mesh, as shown in RIG. 9. Gear 101 is keyed to shaft 11 while gear 102 is keyed to drive shaft 104 which is axially aligned with shaft 12. Also `keyed to shaft 104 is gear 1`7 in mesh with gear 22 connected through clutch 107 to counter shaft 108 having gear 23 keyed thereto. Knob 105 and its rearward extension 106 are keyed to shaft 104 at its forward end. Pin 111 extends radially from extension 106 and its engageable with stop 112. Radial arm 113 keyed to shaft 104 at its rear end is provided with rearwardly extending projection 114 engageable with forward projection 115 on gear 21.

In operation, when reset knob 105 is pushed rearward or in the direction of arrow B, pin 111 moves into the same plane as stop 112 and the rearward tip of element 114 moves into the plane of element 115. In addition, gear 102 becomes disengaged from gear 101. Rotation of knob 105 in the counterclockwise direction indicated by arrow C turns number disk 14 and spiral light aperture disk 16 until element 111 engages stop 112 at which time the two rightmost figures on screen 34 will be 00. During this counterclockwise movement of knob 105 there is a point where element 114 engages element 115 and thereafter number disk moves counterclockwise also stopping at the time when element 111 engages stop 112 at which time all four figures appearing on display screen 34 will be 0. While element 114 rotates gear 21 in a counterclockwise direction, clutch 107 permits slippage of gear 22 relative to shaft 108 so that rotation of shaft 108` is not inhibited by the engagement of gears 17 and 22. A spring (not shown) biases knob 105 in a forward direction when it is released so that gears 101, 102 mesh and as shaft 11 begins to rotate.

Thus, it is seen that the instant invention provides a novel mechanical-optical rotary shaft counter that is quiet operating, reliable and capable of extremely high speed operations principally by virtue of the fact that there are no mechanical stepping elements.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A measuring device including an input member 'to which power is applied for driving said device and to be driven in accordance with information being measured by said device so that the position of said input member is a function of the information being measured; a rst, a second, and a third member; drive means interconnecting said input member to the others of said members for coordinated operation whereby continuous movement of said input member results in continuous related movements of each of the other members with said lirst member moving faster than said second member; a first and a second set of indicia elements carried on said first and said second members respectively, and continuously movable therewith; an aperture formed by means including a portion carried on said third member and continuously movable therewith; said first, second and third members disposed so that for all positions of said input member those of said indicia elements of said yfirst and second sets which combine to produce an output indicating the position of said input member, are aligned with said aperture.

2. A measuring device as set forth in claim 1 in which the rst, second and third members are plate-like elements positioned in parallel planes and mounted for rotation about rotational axes perpendicular to said planes; the elements of said first set arranged in a circular array about the rotational axis of said first member and the elements of said second set arranged in a circular array about the rotational axis of said second member; said portion of said aperture-forming means carried by said third member comprising a spiral formation arranged about the rotational axis of said third member; said rotational axis of said third member being laterally spaced with respect to the rotational axes of both said lirst and second member.

3. A measuring device as set forth in claim 2 in which said rotational axes of said first and second members are axially aligned.

4. A measuring device as set forth in claim 3 in which during each revolution of said rst member said aperture moves gradually from a first to a second position and during a transition interval at the end of a revolution returns abruptly to said first position with a particular element of said second set remaining aligned with said aperture during said revolution.

5. A measuring device as set forth in claim 4 in which said lirst and said third members rotate at the same angular speed; said spiral formation comprising essentially a single turn having overlapping ends aligned with indicia elements of said sets during said transition interval.

6. A measuring device as set forth in claim 3 also including optical display means comprising a source for projecting a light beam, a display surface, a lens system directing said light beam along a path extending through said first, second, and third members to said display surface; for each given instant said path extending through said aperture and regions of said first and second members having those of said indicia elements which combine to indicate the position of said input member at said given instant.

7. A measuring device as set forth in claim 6 in which said spiral formation is transparent and said indicia elements of each 0f said sets are transparent areas in an opaque iield.

8. A measuring device as set forth in claim 7 in which said spiral formation includes edge boundary strips that are less transparent than the main section of said spiral formation located between said strips; said main section passing a light band which is projected over a sufiicient area of said display surface high to permit projection of a complete one of said indicia elements on said display surface, said edge boundary strips being of sufiicient transparency to permit viewing of said indiciav elements at said display surface; said spiral formation being wide enough so that for all positions of said first member at least one entire indicia element of said rst set is viewable at said display surface.

9. A measuring device as set forth in claim 5 in which the indicia elements of said first set include a blank region aligned with said aperture during said transition interval; said indicia elements of said first set, including said blank region, exceeding by one the number of indicia elements of said second set.

10. A measuring device as set forth in claim 5 also including reset means comprising iirst means for disconnecting said input member from said first member and rotating the latter to a zero position; second means operated by said first means to engage said second member when said first and seconds members are in predetermined angular alignment and rotate the second member at the same speed as said first member until the latter reaches said zero position.

References Cited UNITED STATES PATENTS 2,392,461 1/1946 Clifton et al. 73-81 FOREIGN PATENTS 1,046,894 12/1958 Germany 353-41 SAMUEL S. MATTHEWS, Primary Examiner 

